If you did not format your drive and do a fresh XP install, there could be lingering Windows 98 drivers which will cause problems under XP. Boot into XP safe mode (hit F8 before XP boots) and go into your device manager and remove any MOTU MIDI devices shown. They will probably appear under Sound, Video, and Game controllers, USB controllers, or Uknown Devices. Then, when you reboot, it should ask for the current drivers and install them properly.